Meeting the Paris Agreement on Climate: Exploiting Earth System Models to determine the role of future land-use change

该奖学金将利用下一代气候模型，对英国土地利用变化政策（如减少森林砍伐和增加造林）的潜力进行首次评估，以帮助社会实现气候目标。三年前，在巴黎签署了一项雄心勃勃的全球协议，试图将气候变化导致的全球变暖限制在前工业化时期的2摄氏度以内；我们已经差不多是1摄氏度了。科学家可以使用详细的计算机模拟来试图了解未来气候可能发生的变化；到2050年，在成功地将变暖限制在《巴黎协定》规定的水平的情况下，社会不再是温室气体的净排放国，但我们从空气中吸收的温室气体比我们排放的要多。全球温室气体排放达到峰值所需的时间越长，我们需要的温室气体减排或负排放的程度就越大。有几种方法可以实现净负排放。目前，技术上最可行的是通过消除森林砍伐，进行大规模的造林和再造林。另一种依赖于未来技术发展的方法是燃烧生物质来产生能量，然后捕获并储存任何本应在深层地质储层中排放的温室气体。初步估计表明，为了通过这一过程产生足够的负排放，需要一个澳大利亚大小的区域专门用于种植能源作物。我之前的研究表明，由于植物和大气成分之间的相互作用，森林和其他植被可以对气候产生降温影响。植物向空气中排放各种各样的气体，这些气体赋予了松林独特的气味。这些气体参与了复杂的化学反应，可以继续形成粒子，作为云滴形成的种子。这个过程很重要，因为云中的水滴越多，云就越亮，反射太阳能量的能力也就越强，从而有助于冷却气候。我之前的工作也表明，随着全球气温的上升，这些天然颗粒的冷却效应可能会变得更强；这可能会略微抑制温室气体浓度升高引起的变暖。在我的奖学金期间，我将开发和使用英国第一个全耦合地球系统模型（UKESM）来评估未来土地利用变化的潜力，以帮助实现全球气候目标。我将与国际组织合作，确保UKESM包含对生物圈-大气相互作用的最先进的科学理解；使用完全耦合的ESM来探索这一点，代表了我们评估对未来气候的影响的方式的一个步骤变化。

This Fellowship will exploit the next generation of climate models to make the UK's first assessment of the potential for land-use change policy (e.g., reduced deforestation and increased afforestation) to help society meet climate targets. Three years ago, an ambitious global agreement was signed in Paris to try and limit warming due to climate change to less than 2 degrees since the pre-industrial period; we're already at almost 1 degree. Scientists can use detailed computer simulations to try and understand what could happen to the climate in the future; by 2050 in scenarios that succeed in limiting warming to the levels specified in the Paris Agreement, society is no longer a net emitter of greenhouse gases (GHGs), but we are drawing more GHGs out of the air than we're putting in. The longer it takes global GHG emissions to peak the greater the extent of GHG removal, or negative emissions, we will require. There are a couple of ways that net negative emissions could be achieved. Currently, the most technologically feasible is through eliminating deforestation and engaging in large-scale afforestation and reforestation. Another way, which relies on future technological developments, is to burn biomass to generate energy and then capture and store any GHGs that would have been emitted in deep geological reservoirs. Initial estimates suggest that an area the size of Australia would need to be dedicated to growing energy crops in order to generate sufficient negative emissions through this process. My previous research has demonstrated that forests and other vegetation can have a cooling impact on the climate because of interactions between plants and the composition of the atmosphere. Plants emit a wide range of gases into the air, the kind that give pine forests their distinctive smell. These gases take part in complex chemical reactions and can go on to form particles that act as seeds for cloud droplet formation. This process is important because the more droplets there are in a cloud, the brighter and more reflective of the Sun's energy it is, helping to cool the climate. My previous work also indicates that the cooling effects due to these natural particles could become stronger as global temperatures rise; this may act to slightly dampen the warming caused by higher GHG concentrations. During my Fellowship, I will develop and use the UK's first fully-coupled Earth System Model (UKESM) to assess the potential for future land-use change to help meet global climate targets. I will work with international organisations to ensure that UKESM contains state-of-the-science understanding of biosphere-atmosphere interactions; using a fully-coupled ESM to explore this represents a step-change in the way we can evaluate impacts on, and of, future climate.